a. Field of the Invention
The present invention relates to irrigated catheter assembly systems and methods for ablating tissue using controlled irrigation flow. The present invention further relates to open irrigated catheter ablation systems having irrigation fluid flow that may be regulated in connection with a predetermined temperature threshold.
b. Background Art
Electrophysiology catheters are used for an ever-increasing number of procedures. For example, catheters are used for diagnostic, therapeutic, and ablative procedures, to name just a few procedures. Typically, a catheter is manipulated through the patient's vasculature to an intended site, for example, a site within the patient's heart. The catheter commonly carries one or more electrodes, which may be used for ablation, diagnosis, and/or other treatments.
There are a number of methods used for ablation of desired areas, including for example, radiofrequency (RF) ablation. RF ablation is accomplished by transmission of radiofrequency energy to a desired target area through an electrode assembly to ablate tissue at a target site. Because RF ablation may generate significant heat, which if not controlled could result in tissue damage, such as steam pop, tissue charring, and the like, it is often desirable to include a mechanism to irrigate the target area and the device with biocompatible fluids, such as saline solution. The use of fluid irrigated ablation catheters can also prevent the formation of soft thrombus and/or blood coagulation.
Generally, there are two classes of irrigated electrode catheters, open and closed irrigation catheters. Closed ablation catheters can circulate a cooling fluid within the inner cavity of the ablation electrode. Open ablation catheters can deliver the cooling fluid through open outlets or openings on the surface of the electrode. Open ablation catheters use the inner cavity of the electrode, or distal member, as a manifold to distribute saline solution (or other irrigation fluids known to those skilled in the art) to one or more passageways that lead to openings/outlets provided on the surface of the electrode. The saline thus flows directly through the outlets of the passageways onto or about the distal electrode member. This direct flow through the distal electrode tip lowers the temperature of the distal tip during operation, which may make accurate monitoring and control of the ablation process somewhat more challenging.
While open irrigated ablation catheters may improve the safety of RF catheter ablation by preventing protein aggregation and blood coagulation through the dissipation of heat by providing fluid to the site during the ablation procedure, direct contacting fluid irrigation has the tendency to cool the electrode temperature dramatically during ablation procedures. The irrigation fluid flow ultimately cuts off the electrode temperature from rising, which may result in increased (and possibly more than desirable) ablation in a target area. As such, it can be desirable to control and more accurately monitor the temperature of an electrode performing ablation.